This invention relates to medical electronics in general, and more particularly to an improved digital X-ray image processing system, that utilizes the visual output of an image intensifier, designated fluoroscope, for generating an analog video input signal which is subsequently digitized and manipulated in the digital domain and, finally, reconverted to analog video for review in real time or digitally stored for post examination by physicial, diagnostician.
The use of fluoroscopy in medical dignostic procedures through which invisible X-rays are directed through a patient and converted into visual images by an image intensifier tube, (fluoroscope) which images, through the inclusion of optics, are directed into video or film containing mechanisms, is well know in prior art. A good explanation of the manner in which such is used in the prior art is described in U.S. Pat. No. 4,193,089. While this analog video image permits and examination of the results in real time, the analog film images require subsequent chemical processing and, therefore, are used later for more detailed diagnosis. Digital X-ray or digital radiography utilizes the basic components of fluroscopy up to and including the image intensifier and analog video which is converted into the digital domain for computer manipulation that enhance the basic signal information and allow a series of algorithms to be applied in various real time or post processing steps, determined by the examining physician.
Angiography, the X-ray examination of the major blood vessels using contrast agents, is utilized when a patient is suspected by a physician of having some form of cardiovascular or arteriosclerotic disease. Among the most common procedures are the coronary arteries which supply blood to the heart muscle, the carotids which are the major arteries in the neck providing blood to the brain, the cerebral arteries themselves and the renal arteries which provide blood to the kidneys. The arteries are commom sites of arteriosclerosis which, if properly diagnosed, can be treated surgically or with drugs. Conventional X-ray angiography requires a surgical procedure to permit the insertion of as catheter and injection of contrast media directly into the artery to be examined. This procedure is uncomfortable for the patient, involves a degree of risk and requires hospitalization for three days. Therefore, only highly symptomatic patients are referred for such procedures. Digital subtraction angiography (DSA) permits contrast media to be injected interavenously in certain procedures rather than by arterial catheterization, so that the procedure can be done on an outpatient basis. The computer memory records and X-ray image of the area of the body under study and then subtracts this information from a second X-ray image taken after injection of the contrast media, thereby eliminatinng anatomical structures. Attempts to record coronary artery information with intravenous contrast injections has yet to prove successful. Limited digital recording media and limited transfer rates to digital media has further limited the usefulness of digital techniques in studing the coronary arteries.
There is, thus, a need for an improved fluoroscopy system which permits viewing and recording of fluoroscopic images, in real time via a video display, as a radio-opaque material is injected into or ingested by a patient and the patient irradiated with X-rays, which has sufficient contrast at the time to permit the physician to be assured that the procedure was successful and does not have to be repeated. Furthermore, there is a need to be able to store responses and re-study these television images instead of or in conjunction with film images at a later time.